The present application relates to an electrolyte containing halogenated cyclic ester carbonate and a secondary battery including the same.
In recent years, portable electronic devices such as combination cameras, digital still cameras, mobile phones, and notebook personal computers have been widely used, and it is strongly demanded to reduce their size and weight and to achieve their long life. Accordingly, as a power source for the portable electronic devices, a battery, in particular a light-weight secondary batter capable of providing a high energy density has been developed.
Specially, a lithium ion secondary battery using insertion and extraction of lithium ions for charge and discharge reaction, a lithium metal secondary battery using precipitation and dissolution of lithium metal and the like are extremely prospective, since such secondary batteries are able to provide a higher energy density compared to a lead battery and a nickel cadmium battery.
The secondary battery includes an electrolyte together with a cathode and an anode. The cathode has a cathode active material layer on a cathode current collector. The anode has an anode active material layer on an anode current collector. The electrolyte contains a solvent and an electrolyte salt.
The electrolyte functioning as a medium for charge and discharge reaction largely affects performance of the secondary battery. Thus, various studies have been made on the composition of the electrolyte. Specifically, to improve the cycle characteristics and the like, as a solvent, halogenated carbonate such as trifluoropropylene carbonate, fluoroethylene carbonate, and difluoroethylene carbonate is used (for example, refer to Japanese Unexamined Patent Application Publication Nos. 2001-297790, 2005-190978, 2007-019027, and 07-240232). Further, carbonate having a halogenated alkyl group is used (for example, refer to Japanese Unexamined Patent Application Publication No. 2006-210161).